Evaluation of the Acaricidal Effectiveness of Fipronil and Phoxim in Field Populations of Dermanyssus gallinae (De Geer, 1778) from Ornamental Poultry Farms in Italy

Abstract

The poultry red mite Dermanyssus gallinae is the most important blood-sucking ectoparasite in egg-laying hen facilities. The aim of this study was to evaluate the in vitro acaricidal activity of different concentration of authorized (phoxim, ByeMite®, 500 mg/mL) and unauthorized (fipronil, Frontline® 250 mg/100 mL spray) molecules on 14 field isolates of D. gallinae collected from different ornamental poultry farms from different Italian regions. The sensitivity test was performed by contact exposure to four concentrations of each insecticide diluted at 1:5 (10,000-2000-400-80 ppm for phoxim, 500-100-20-4 ppm for fipronil) on a filter paper. The effectiveness of the treatment was significantly (p < 0.0001) associated with the dose of the pesticide used. Considering the mean lethality, phoxim has greater efficacy compared to fipronil (p < 0.001). A great variability of lethality rate was observed with the increase in fipronil dilution; conversely, for phoxim, some outliers were observed, particularly in one farm, suggesting the hypothesis that a certain degree of resistance in the mite population could occur possibly as a consequence of the continual contact with the molecule. This underlines the importance of the use of licensed products administered at correct dosages and the need for alternative molecules to avoid the onset of drug resistance phenomena.

Blood-feeding adaptations and virome assessment of the poultry red mite Dermanyssus gallinae guided by RNA-seq

“…While we could see clear time- and dose-dependent lethality of mites post micro-injection of Fluralaner and Ivermectin, similarly to previous studies exploiting a different route of administration 87 , 88 , we did not observe the acaricidal effect of Fipronil administered through micro-injection. This observation may be in line with previously reported lower and heterogenous sensitivity of D. gallinae mites to topical exposure to Fipronil solution 89 . While we have no knowledge of Acari-specific chloride channels, an increasing body of work is available on pH-sensitive chloride channels in other invertebrates.…”

Advances in Non-Chemical Tools to Control Poultry Hematophagous Mites

“…Furthermore, one of the main concerns in using acaricides is the selection of resistant mite populations [7,51,53,86]. These products are used indiscriminately and many producers ignore the legal restrictions in their countries [7,9,19,84], and many of the active compounds are banned in Europe and/or in EU member states [19,50]. * Result considering higher dose and after the end of the last treatment dose; # 100% mortality dilution of mites.…”

“…Fipronil is forbidden to be used in animal used as food [19]. Products belonging to the class of carbamates, organophosphates, and pyrethroids have been banned in the EU for use against D. gallinae.…”

“…The elimination or control of these mites has become increasingly difficult due to their resistance to the chemical products available on the market [6,7,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] combined with a change in the system of raising animals in battery cages to that of enriched cages or "cage free" systems that make it difficult to control and observe the animals as they start to live free in sheds and roam freely in pastures [33][34][35]. Due to this scenario, new technologies to control the hematophagous mites without the use of chemical acaricides are needed, such as plant-derived products, entomopathogenic fungi, diatomaceous and silica-based products, semiochemicals, and vaccines.…”

Public Health Threats from Pet Bird Zoonoses

“…Other bird species, including pet birds, may also contract the disease. Despite D. gallinae typically being nocturnal, the effects of infection can be seen during the day [40,41]. It is known that D. gallinae can spread several zoonotic pathogenssuch as C. psittaci [1].…”